Download Chapter 9 - Photosynthesis

SBI4U- Photosynthesis
2 Sets of Reactions in Photosynthesis
Light-Dependent Reactions
-The light-dependent reactions require _______
-These reactions occur in the ________________________
-They produce _________ and __________ which are needed
to produce glucose in the light-independent reactions
Light-Independent Reactions
-Light-independent reactions occur in stroma of the
chloroplast in light or dark conditions.
-They function to reduce CO2 to glucose.
Overview of Reactions in Photosynthesis:
6CO2 + 6H2O + Energy  C6H12O6 + 6O2
How does a Plant turn light from the sun into useable Energy?
1. Photosynthetic pigments in the membrane of the thylakoid form a unit called an
__________________________
2. A ___________________________ within the antenna absorbs a photon of light energy. The energy
from that pigment molecule is passed to neighboring pigment molecules and eventually makes its way
to pigment molecule called the ___________________________
3. The reaction center molecule becomes excited (energized), it loses an electron to an electron acceptor.
Photosystems
 The antenna and the reaction center are called a _______________
 There are two kinds of photosystems in plants:
1. Photosystem I: Contains a __________________ reaction center that absorbs
____________ light
2. Photosystem II: Contains a ______________ reaction center that absorbs
____________ light
4. The ________________________________________________ from the reaction center.
 As a result of gaining an electron (reduction), the electron acceptor becomes a high-energy
molecule.
 Recall that oxidation is the loss of an electron and the ____________________. Reduction is
the gain of an electron and energy. Energy is transferred with the electron.
Light Dependent Reactions
1. Pigments in Photosystem II absorb a _________________ of energy from __________
2. Energy is passed from these pigments to the ____________________________ (P680)
3. The reaction center passes the electron to the _________________________________
4. The electron carrier ________________ when it gains an electron and uses this energy
to ________________________________________________
5. The electron is then passed to a second electron carrier
6. The second electron carrier also uses its energy to pump H+ ions into the thylakoid
lumen
7. The electron is then passed to a third electron carrier
8. The third electron carrier also uses its energy to pump H+ ions into the thylakoid lumen
9. The H+ ions in the lumen want to get out! ____________________ pumps them into the
___________________, using the energy released to create __________ (This process
is called chemiosmosis)
10. The electron is passed from the electron carrier to the _______________ complex in
photosystem I
11. Pigments in Photosystem I gain energy from absorbing a photon of light and the energy
is passed to the P700 reaction center
12. The excited electron from P700 is passed to an electron carrier
13. The electron is then passed to NADP+ (along with an H+ ion) to form a high energy
NADPH molecule
14. The electron is then passed to __________________ (along with an H+ ion) to form a
high energy NADPH molecule
15. The electron lost by Photosystem II needs to be replaced! Water is broken down to form
2 electrons (This reaction also produces Oxygen which will be released by the plant
thylakoid lumen
Homework: Draw your own
diagrams of the electron
transport chain!
-Make sure to label the 15
steps!
-You also must label (at least)
the following components:
thylakoid lumen, thylakoid
membrane, stroma, electron
carrier, Photosystem I and II,
P700 & P680 reaction centers,
ATP Synthase, pigments,
antenna
SBI4U: Photosynthesis II
Light Independent Reaction- The Calvin Cycle
Purpose:
– To create _________________________ from _____________
– This reaction requires _______________________
– The energy required to power this reaction comes from _________ and
_______________ created in the ___________________
Location:
– The __________________ of the plant cell
Calvin Cycle Terms:
1. CO2 Fixation: The bonding of ____________ to an ______________________ to make
a larger molecule.
2. RuBP: A ______________ molecule found in the Calvin Cycle
3. RuBP Carboxylase: An ______________ that catalyzes the reaction between ________
and _____________
4. PGA: A _______________ molecule found in the Calvin Cycle
2
5. PGAL: A ________________ molecule found in the Calvin Cycle (2 PGALs join to make
1 __________________ molecule)
• CO2 fixation: the bonding CO2
CO Fixation
to an orga
molecule to make a larger molecule.
• C5 + CO2  C6
“C5” is an abbreviation that means that this molecule has 5
carbon atoms. The oxygen and hydrogen atoms are not written.
Carbon Fixation
Light | Pigments | Overview | Chloroplast | Photosystem II | Electron Transport System | Photosystem I | Calvin Cycle | Photorespiration | C4
The Calvin Cycle
Steps of the Calvin Cycle:
1. CO2 binds to RuBP making a C6 molecule
2. The C6 molecule splits into 2 C3 compounds of PGA
3. The 2 molecules of PGA are reduced to PGAL
 This reaction requires energy (the ATP and NADPH formed in the light reactions are
used!)
4. 2 molecules of PGAL are used to form photosynthesis
5. The remaining 10 molecules of PGAL are re-arranged into 6 molecules of RuBP
 This reaction requires energy (the ATP and NADPH formed in the light reactions are
used!)